81 x 9 = 801. What must you do to make the this equation true?

In the image given, you can find several triangles. Can you count them all?

Replace the question mark with the correct number.

2 + 2= 4
3 + 3= 18
4 + 4= 48
5 + 5= ?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

What does the below rebus puzzle mean?

How can a man go eight days without sleep?

You can hear me, but you can't touch or see me.

What am I?

Let's play a word game. Following are some meaningless words that can be completed by adding random letters on either side of the word.

For example, the word "rdo" can be formed into "pardon".

Using the same technique, can you complete the given words?
ecalc
airb
rinci
tibac
uidel
gorit
igna
eyho

Which five letter word can be added at the end of below word to form a
valid word?

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Which is the smallest number that you can write using all the vowels exactly once?